1. Field of the Invention
The invention relates to a mobile communication system, to a method and to an alternative network gateway unit for processing a call between a mobile services switching centre and a gateway mobile switching centre via an alternative network.
2. Description of the Invention
A gateway mobile switching centre and a mobile services switching centre, which are part of a mobile communication system, e.g. like the GSM system, are able to forward or to receive a call via a network, like an integrated services digital network ISDN or an PSTN. The method for forwarding or receiving the call via such a network and the network gateway unit therefore are specified in the standard of the mobile communication system, e.g. the GSM system or the D-AMPS system. In this environment the ISDN system or the PSTN system is used to relay the call between the mobile services switching centre, which is serving a mobile subscriber and the gateway mobile switching centre, which contains information about the mobile subscriber and which relays the terminating call.
There is no further network known which is specified in the prior art and via which a call could be relayed between the mobile services switching centre and the gateway mobile switching centre. Therefore a call could only be relayed over the networks mentioned and specified in the standards. Therefore it is not possible according to the prior art, to relay the call via an alternative network and to take advantage out of the relaying of a call via such an alternative network.
Therefore it is an object of the present invention to provide a system, a method and an alternative network gateway unit to process a call via an alternative network.
This is achieved according to the system, subsystem, method, and gateway unit of the present invention.
It is an advantage of the present invention that a call can be routed directly via an alternative network and that a PLMN (Public Land Mobile Network) can directly interwork with and take advantage of routing calls through such alternative networks.
As the number of alternative networks or alternative network parts is increasing and as these networks offer an increasing number of functionality, it is advantageous according to the invention to make use of this functionality.
It is further advantageous that according to the invention a call could be relayed via any upcoming new alternative network. The alternative network gateway unit provides the possibility to adapt to the configuration of the alternative network and to relay calls via such a network.
According to one embodiment it is advantageous to use a Voice-over-IP network, or a FAX-over-IP network, or a Multimedia-over-IP network or a data-over-IP network as an alternative network. These networks advantageously provide a plurality of services in one network and this in an effective and cost efficient way. E.g. the provision of a voice-over-IP network is easy to build up compared to build up a public switched telephone network (PSTN). A reason for this is that different bearer services are integrated and that one single network will be used for data and for speech. Both speech and data is transferred via this one network.
According to another embodiment an alternative network gateway unit is connected to a gateway mobile switching centre or to a mobile services switching centre, which means that said alternative network gateway unit is positioned between the alternative network and the
According to another embodiment an alternative network gateway unit is a part of the gateway mobile switching centre or which is part of the mobile services switching centre. This means that the alternative network gateway unit is incorporated into the gateway mobile switching centre or the mobile services switching centre and therefore a new enhanced gateway mobile switching centre or enhanced mobile services switching centre is built up.
According to yet another embodiment the method for processing a call could be advantageously used in a system working according to the GSM standard or according to the D-AMPS standard or according to the UMTS standard.